10 Most Adult Moments In Batman: The Animated Series
9. Mr. Freeze's Origin - Heart Of Ice
Before he was even brought up in the animated series, Mr. Freeze was usually meant to be a punchline in the comics, being nothing more than just a man with a sort-of cool gun.
This episode - courtesy of writer Paul Dini - is where the depth comes in though.
Being nothing more than a simple scientist, this was never a guy who wanted to hurt anybody... he was just a brilliant man who fell on hard times and had to do what he could to save the woman he loves. It also helps to have the voice of Michael Ansara behind everything, who sounds like he's performing on a stage in the vocal booth whenever you hear him.
Hell, just the reading of lines like, "pray that you hear me somehow...someplace where a warm hand waits for mine", is one of the most powerful gut punches you will ever get.
Even though the traditional Mr. Freeze in the comics had a completely different origin, this is now the official way that the Caped Crusader's cold-hearted adversary came to be.